The present invention relates to a steel laminate gasket for an internal combustion engine, which can provide wide and high sealing pressure to securely seal around a hole.
The steel laminate gasket of the present invention may be used widely, such as a regular gasket situated between two engine blocks, such as a cylinder head gasket and a manifold gasket. When the gasket of the present invention is used as a cylinder head gasket, the gasket may seal around cylinder holes Hc, water holes Hw, oil holes Ho, bolt holes Hb and the like, as shown in FIG. 1. However, it is preferable to seal around a relatively large hole, such as a cylinder hole Hc.
In a gasket, a main subject of a gasket is to securely seal around a hole. Therefore, when a gasket is designed, attention has been paid how a portion around a hole is securely sealed. In this respect, there have been proposed many methods.
One of the conventional methods to seal around a hole is to form a bead around a hole. As shown in FIG. 2, for example, a gasket 20 comprises an upper plate 21, a lower plate 23, and a middle plate 22 having a bead 22a around a cylinder hole Hc. In the gasket 20, the bead 22a only provides a sealing pressure around the cylinder hole Hc. Therefore, fluid passing through the hole Hc may permeate through the plates. The sealing ability of the gasket 20 is not good.
In view of the prior art, a gasket 25 as shown in FIG. 3 has been proposed in Ser. No. 193,215 filed on May 11, 1988. The gasket 25 comprises an upper plate 26 with a curved portion 26a and a flange 26b, and a lower plate 27. The gasket 25 can securely seal around the hole Hc. However, since an area around the hole Hc is only sealed by the curved portion 26a, the sealing area that forms sealing pressure is relatively narrow. Further, since the curved portion may strongly abut against the engine block, in case the engine blocks are formed of an aluminum alloy, the engine blocks may deform at the curved portion. Therefore, a gasket with a relatively wide sealing area without affecting the engine blocks has been desired.
In a patent application Ser. No. 243,528 filed on Sept. 12, 1988, a gasket can provide relatively strong sealing pressure around a hole. However, in case the gasket is not completely tightened, creep relaxation may occur around a hole in a long usage.
Accordingly, one object of the present invention is to provide a steel laminate gasket, which can provide wide and high sealing pressure around a hole to be sealed.
Another object of the present invention is to provide a steel laminate gasket as stated above, which can be easily tightened strongly to seal around a hole without causing any damage to engine blocks.
A further object of the present invention is to provide a steel laminate gasket as stated above, which can provide a second seal around a hole to be sealed.
A still further object of the present invention is to provide a steel laminate gasket as stated above, which can be easily and economically manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.